The attorneys said in a motion that their preliminary survey of the attitudes of potential jurors in Boston, Springfield, New York City and Washington found Washington would be the most favorable location for a trial.

The lawyers said Boston ranked as the most prejudiced and Washington the least on critical measures including awareness and knowledge of the case, pre-judgment of Tsarnaev's guilt and support for giving him the death penalty if he were convicted.

Authorities say Tsarnaev and his brother planted two pressure cooker bombs near the finish line of the 2013 marathon, killing three people and injuring more than 260 others. Tsarnaev's brother died following a shootout with police several days later.

Tsarnaev has pleaded not guilty to 30 federal charges. His trial is expected to begin in November.

The motion noted that the bombings occurred as thousands of Boston residents and other people from the region had gathered to celebrate the marathon, Patriots' Day and a Boston Red Sox game. It cited "the indelible fear" that people's friends and relatives could have been killed or injured and the trauma people experienced as police sought the perpetrators. It noted that hundreds of thousands of Boston-area residents were asked to shelter in place "during the climactic final day of the search" before Tsarnaev was captured hiding in a boat in someone's backyard.

The lawyers acknowledged that trials are seldom moved but noted that one exception was that of Oklahoma City federal building bombing suspect Timothy McVeigh. They said "the community impact here is even greater than that present in McVeigh."

They said more work needs to be done on the impact of media coverage and the results of their survey. Their filing had been expected, and federal prosecutors will be allowed to respond.

At a hearing earlier Wednesday, a federal judge ruled that "betrayal of the United States" may not be among the factors prosecutors cite when arguing that Tsarnaev should get the death penalty if convicted.

U.S. District Court Judge George O'Toole said it was "highly inappropriate" for prosecutors to draw a distinction between a "naturalized" and a "natural-born" U.S. citizen.

Federal prosecutors have argued, in part, that Tsarnaev deserves the death penalty because he betrayed his allegiance to the country that granted him asylum and citizenship.

"Just seven months after swearing an oath to defend his adopted country and stand by his fellow Americans, Tsarnaev violated the oath by attacking America and terrorizing and murdering people on American soil," U.S. Attorney Carmen Ortiz's office wrote in an April filing. "He did so, by his own account, to punish America for the actions of American soldiers who, in fulfilling their own oaths to protect and defend the Constitution, were waging a war against terrorism overseas."

Tsarnaev, 20, lived in the former Soviet republic of Kyrgyzstan and later in Russia before moving to the U.S. with his family at age 8.

Tsarnaev's attorneys have said the government's argument is unprecedented in death penalty cases.

In other matters Wednesday, the judge denied a request by Tsarnaev's lawyers to allow them to meet with their client and his sisters in prison without federal agents present.

Instead, he accepted a compromise offered by prosecutors: assigning an FBI agent or other federal official not assigned to the case for security purposes.